S21
type: MusicGroup
description: S21 or S-21 may refer to: Automobiles Chery S21, a city car Sisu S-21, a Finnish lorry Aviation De Schelde S.21, a proposed Dutch fighter Rans S-21 Outbound, an American homebuilt aircraft
popularity: 2
followers: 32
additional property: CopyrightID
additional property: CopyrightChainExplorerURL
  type: PropertyValue
  value: https://explorer.copyrightchains.com/tx/0xaaf2b030c90db3646f670cd5193de452d930e78d2034f5f1efc9f307ae897c45
additional property: OTSHash
additional property: OTSBitcoinBlock
  type: PropertyValue
  value: 954008
additional property: OTSBitcoinBlockVerifyURL
  type: PropertyValue
  value: https://blockstream.info/api/block-height/954008
additional property: OTSProofURL
  type: PropertyValue
  value: https://artists.proofprofile.net/proofs/artist/334df0e1-25ea-40ae-b361-2d44b863e52b.ots
additional property: OTSRecordURL
  type: PropertyValue
  value: https://artists.proofprofile.net/proofs/artist/334df0e1-25ea-40ae-b361-2d44b863e52b.json
additional property: OTSVerificationAPI
  type: PropertyValue
  value: https://artists.proofprofile.net/api/v1/bot/ots/verify/artist/334df0e1-25ea-40ae-b361-2d44b863e52b
additional property: OTSTimestamp
  type: PropertyValue
  value: 2026-06-16T21:31:27Z
additional property: OTSCanonicalRecord
additional property: OTSVerifyInstructions
  type: PropertyValue
  value: 1. Compute SHA-256 of OTSCanonicalRecord value → must equal OTSHash 2. Open OTSProofURL → extract Bitcoin block number → must equal OTSBitcoinBlock 3. GET OTSBitcoinBlockVerifyURL → returns the Bitcoin block hash at height OTSBitcoinBlock; GET https://blockstream.info/api/block/{that hash} → its timestamp must match OTSTimestamp 4. Read CopyrightID inside OTSCanonicalRecord → must equal the CopyrightID above 5. GET OTSVerificationAPI → pre-computed 6-check result from server 6. If all match: this entity was registered on CopyrightChains at OTSTimestamp, independently verifiable on Bitcoin Note: an OTS proof may carry multiple Bitcoin attestations; OTSBitcoinBlock is the earliest confirmed one — a later attestation inside the proof corroborates it and is not a mismatch
subject of: OpenTimestamps Proof of Existence
  type: DigitalDocument
  encoding format: application/vnd.opentimestamps.ots
  description: Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xaaf2b030c90db3646f670cd5193de452d930e78d2034f5f1efc9f307ae897c45. Chain 2 (Bitcoin): anchored in block 954008 (2026-06-16T21:31:27Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/334df0e1-25ea-40ae-b361-2d44b863e52b.json and https://artists.proofprofile.net/proofs/artist/334df0e1-25ea-40ae-b361-2d44b863e52b.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).
  date published: 2026-06-16T21:31:27Z
album: VICE CITY
  type: MusicAlbum
  date published: 2024-11-20
album: VA CHINGAR
  type: MusicAlbum
  date published: 2025-02-01
album: NELFV
  type: MusicAlbum
  date published: 2025-03-22
album: TAL COMO ERES
  type: MusicAlbum
  date published: 2025-05-09